677 ISSN 2070-2051, Protection of Metals and Physical Chemistry of Surfaces, 2019, Vol. 55, No. 4, pp. 677–681. © Pleiades Publishing, Ltd., 2019. Nickel Nanoparticle Catalyzed Growth of Multiwall CNTs on Copper thin Films Substrate Kimia Nikpasand a , Seyed Mohammad Elahi a, *, Amir Hossein Sari a , and Arash Boochani b a Department of Physics, Faculty of Sciences, Science and Research Branch, Islamic Azad University, Tehran, Iran b Department of Physics, Kermanshah Branch, Islamic Azad University, Kermanshah, Iran *e-mail: smohammad_elahi@srbiau.ac.ir Received December 19, 2018; revised January 23, 2019; accepted February 8, 2019 Abstract—Significant applications of metallic nanocatalysts motivated us to study the role of catalyst contents by choosing Cu–Ni nanocatalyst in synthesizing carbon nanotubes (CNTs). Cu–Ni thin films were prepared by RF sputtering method with different deposition time of Ni. They inserted the prepared catalysts into a quartz tube reactor for carbon nanotubes fabrication. Scanning electron microscopy (SEM) recorded the diameter distribution of multi walled carbon nanotubes (MWCNTs) while atomic force microscopy (AFM) was applied for surface roughness estimation. Both analyses confirm the positive effect of deposition time on the catalytic properties of Cu/Ni nanocatalysts which ends to the improved quality of prepared CNTs. In addition, the structure of multi walled carbon nanotubes were investigated by Raman spectroscopy. Keywords: Cu–Ni nanocomposite, multiwall CNTs, RF-sputtering, AFM, SEM, catalyst properties DOI: 10.1134/S2070205119040130 INTRODUCTION Optical and structural properties of various types of nanostructured materials along with their surface morphology analysis have been studied recently [1– 5]. Among novel nanostructures, carbon nanotubes (CNTs) are the best candidate with their unique prop- erties and simple composition [6]. For example, they can be used as a probe tips for scanning probe micros- copy due to their elasticity. Also, the main part of polymeric materials is carbon nanotubes because of their high thermal conductivity. A lot of theoretical and experimental efforts have been done for CNTs growth along with investigating their properties due to their significant application in industry such as tran- sistors and sensors [7–9]. Several methods have been introduced for fabrication of CNTs in high tempera- ture such as chemical vapor deposition [10], arc dis- charge [11], and laser ablation [12] each have some advantages and disadvantages. One of the suitable methods for fabrication of CNTs on metallic and semiconducting substrates is chemical vapor deposi- tion technique by using catalyst [13]. It should be considered that CNTs quality will directly depend on the applied catalysts which deter- mine number of layers, including Single- and multi- wall carbon nanotubes along with their diameters [14, 15]. Because of their surface to volume ratio, transition metal NPs are good candidate to be used as catalysts [16, 17]. Among various types of transition metals for CNTs production, due to high thermal and electrical conductivity of copper and catalytic properties of nickel, these metals have been chosen as the best can- didate in many reports [18, 19]. Comparing to Ni cat- alysts, Ni-based catalysts including Cu have been shown better catalytic activity [20, 21] which is due to variation of electronic and geometric properties of particles [22]. In the present study, the growth of Cu–Ni nano- catalysts were carried out by RF-sputtering of Cu and Ni targets and this process was repeated for carious deposition time of Ni. After wards, the as-prepared nanocatalysts were applied for the synthesis of multi- wall CNTs. The catalytic activity of Cu–Ni samples and the effect of Ni deposition time on the structural properties of CNTs were evaluated by using X-ray dif- fraction (XRD), Rutherford back scattering (RBS), atomic force microscopy (AFM), scanning electron microscopy (SEM), and raman spectroscopy analysis. Experimental Details The 13.56 MHz RF-sputtering system was applied for preparation of three Cu–Ni NPs samples with dif- ferent deposition time of Ni as 10, 15, and 20 min at room temperature which results in samples with 80, 95 and 120 nm thicknesses of Ni layers and labeled as samples #1, #2, and #3, respectively. The system contained Cu target in the first step and Ni target as the second step placed on the powered electrode. Another electrode was grounded and the NANOSCALE AND NANOSTRUCTURED MATERIALS AND COATINGS